America last night gave the green light to British Airways’ tie-up with American Airlines, bringing to an end a 12-year quest by the UK airline to win approval for the deal.

The US Department of Justice said that the pact would be good for consumers, bringing lower fares, new routes and improved schedules. It agreed to give the airlines’ immunity from US anti-trust laws if they surrendered four pairs of runway slots at Heathrow — a much lower number than expected.

The two carriers are now set to combine their transatlantic divisions, creating a giant operation that will account for just under half of all UK-US traffic, and one quarter of all EU-US passengers.